High progesterone is related to effective human labor. Study of serum progesterone and 5alpha-pregnane-3,20-dione in normal and abnormal deliveries.

BACKGROUND

The role of progesterone levels during human labor is unclear.

OBJECTIVE

To investigate serum concentrations of progesterone and 5alpha-pregnane-3,20-dione in normal and abnormal deliveries.

METHODS

Venous and umbilical cord serum samples were collected from 108 parturient women. In a further 49 deliveries, arterial and venous umbilical cord sera were collected separately. The concentrations of progesterone and 5alpha-pregnane-3,20-dione were determined by radioimmunoassay. The delivery modes studied were: elective cesarean section; oxytocin-resistant dystocia; normal but induced delivery, and normal spontaneous delivery.

RESULTS

Progesterone concentrations in maternal and umbilical serum were higher following normal labor than after dystocia (p<0.005) and elective cesarean section (p<0.005). The maternal and umbilical progesterone concentrations in dystocia and elective cesarean section were between 77-43% of those in normal labor. The concentrations did not vary between gestational weeks 37 and 42, within the different modes of delivery. The 5alpha-pregnane-3,20-dione serum concentration in the fetal compartment was twice that in the maternal compartment (p<0.001); its concentration in venous umbilical serum was higher than in corresponding arterial samples (p<0.001). No distinct differences in the 5alpha-pregnane-3,20-dione serum concentration were found with regard to parity or mode of delivery.

CONCLUSION

High progesterone concentrations during parturition appear to be related to effective labor. The findings support results from in vitro experiments on human term myometrium.